It is easy to imagine Penny Feiwel 60 years ago working on the front lines. Despite being in her 10th decade, she dashes about her flat easily, quick-witted and relaxed. "That photographer of yours," she says laughing, "he had me grinning like an old fool, so I'll probably look 109 instead of just 91!"

Feiwel (nee Phelps) was raised in a working-class family in Tottenham. She worked in factories from the age of 13 and in 1927 began training as a nurse. She went to Spain in 1936 at the suggestion of a "very left-wing friend" after losing her job at the hospital for nursing the Hunger Marchers. "I said, 'What on earth do I want to go to Spain for?' and she said, 'Don't you know there's a war going on!' So off I went to Oxford Street, where I had an interview with Lord Somebody and Lady Somebody, and 24 hours later, I was in Spain."

Feiwel was immediately posted to republican mobile medical units. She couldn't speak Spanish and was a lone young woman, working in non-English-speaking, makeshift hospitals, just 3km behind the front lines. Wasn't she scared? She dismisses the question with an impatient, "Of course not!" However, as a foreign woman, she was subject to greater suspicion of being a spy and she admits that some of her patients and fellow workers had doubts that "such a slip of a girl" could be of much assistance: "But I quickly brought them round... Some of those soldiers were quite rough as well, I can tell you."

In 1937 she was sent to Quintanar as temporary medical officer to the Italian Garibaldi battalion - an extraordinary posting for a young woman. There, she successfully controlled a fever epidemic and was awarded the rank of honorary medical officer. She became Lieutenant Penny Phelps of the Spanish Republican Army, medical officer to the Garibaldi battalion. Her last posting was in 1938, to an all-Spanish medical unit towards Valencia, up in the mountains. All day she could hear the nearby bombing from fascist planes.

It was here that Feiwel endured her second bombing attack - and her worst injuries. "People had always said that when you get injured in the war, it's so quick, you cannot remember. And you know," she says, eyes widening behind her thick glasses, almost in amusement, "I cannot remember for the life of me what I was doing at the time. All I remember is waking up in a barn full of people, all of them crying out, 'Agua, agua!' And I looked down at my body and all I could see was white and red. I said to the orderly: 'Where am I?' He looked at me and said: 'You were one of the lucky ones.' "

Shrapnel from the nationalist bomb had ripped across her arms and chest, and embedded itself in her abdomen. Her wrists still bear the scars. "I didn't realise it until I got married, but because of my injuries I was unable to have children. Bits of shrapnel were still in my abdomen. I'm quite sure my husband would have wanted children."

At this point her voice quietens and her fingers entwine anxiously. She was flown back to England to recuperate and while convalescing she met physician Michael Feiwel. They played tennis together, took long walks and three months later they were married. They celebrated their diamond anniversary in 1998 and he died the following year.

What was it like returning to England? "Well, it was the oddest thing," she says, surprise still in her voice. "I wanted to talk about Spain, but they were only interested in King George's coronation."